The present invention relates to a suction system for an internal combustion engine which has a sub-suction path formed separately from a main suction-path.
Recently, internal combustion engines for automobiles are required not only to purify the exhaust gas but also to improve the rate of fuel consumption. For these requirements, exhaust gas recirculation (EGR) and a lean combustion are frequently employed. It is known that in order to prevent combustion fluctuations and misfiring while satisfying both the requirements for EGR and lean combustion; it is satisfactory to increase the burning velocity.
In order to raise this burning velocity, there have been recently proposed several systems, in which a sub-suction path provided separately from a main suction path is designed to inject a gas into a combustion chamber thereby to generate a swirl of the gases in the combustion chamber.
However, the suction system provided with the sub-suction path is still being developed.